Note: Descriptions are shown in the official language in which they were submitted.
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
METHOD AND APPARATUS FOR MIXING AND APPLYING
A MULTI-COMPONENT COATING'COMPOSITION
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] This application relates generally to a method and apparatus for
applying a multi-component coating of a desired composition over a substrate
and,
more particularly, to a method and apparatus for applying a multi-component
refinish
coating over an automotive substrate.
2. Technical Considerations
[0003] Automotive refinish coatings are used to cover damaged areas of a
vehicle in order to restore the original appearance of the vehicle.
Conventional
refinish coatings are typicaliy supplied to automotive repair shops in the
form of multi-
package systems. An example of one such system is a two-package system, with
one package containing a polymeric material and the other package containing a
catalyst or curing agent. When a refinish coating is to be applied onto an
automotive
substrate, the components in the separate packages are mixed together,
typically at
a particular ratio specified by the coating manufacturer, and the mixed
coating
composition is placed into a container. The container is connected to a
coating
device, such as a pneumatic spray gun, and the mixed coating composition is
spray
applied onto the automotive substrate.
[0004] While generally acceptable for most automotive refinish operations,
this conventional refinish coating method does have some drawbacks. For
instance,
after mixing the separate components together, the pot-life of the resultant
coating
composition is typically limited to only about 30 minutes. By "pot-life" is
meant the
time within which the coating composition must be used before the coating
composition becomes too viscous to be applied due to cross-linking or curing.
Also,
-1-
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
since most refinish coating jobs need only cover a relatively small area of a
vehicie,
the separate packages typically do not contain a large amount of the
respective
coating components. Therefore, for larger jobs, several different batches of
the
coating composition must be consecutively prepared and applied. This batch
mixing
increases the time required to coat a large substrate and requires the coating
process to be intermittently stopped and started while batches of the coating
composition are mixed. As will be appreciated by one skilled in the refinish
coating
art, it would be advantageous to increase the curing speed of the coating
composition to decrease the curing time of the applied coating composition so
that
the applied coating could be more quickly sanded or further coatings applied.
However, increasing the curing speed would also disadvantageously decrease the
pot-life of the mixed coating composition.
[0005] In an attempt to alleviate some of these problems, spray devices have
been developed in which specific amounts of the separate coating components
are
mechanically metered to the spray device to provide a desired coating
composition.
Examples of known coating dispensers are disclosed in U.S. Patent Nos.
5;405,083;
4,881,821; 4,767,025; and 6,131,823.While generally acceptable, the mechanical
pumping and metering equipment required to accurately meter specific amounts
of
the coating components to the spray device add to the overall cost of the
system.
Moreover, the metering equipment must be regularly checked and maintained to
ensure that it is in proper working order to accurately supply the required
amounts of
the coating components to.the spray device.
[0006] As will be appreciated by one skilled inthe automotive refinish coating
art, it would be advantageous to provide a method and/or apparatus for
applying a
multi-component coating onto a-substrate which reduces or eliminates at least
some
of the drawbacks of known coating application systems:
SUMMARY OF THE INVENTION
[0007] A method is provided for applying a multi-component coating of a
desired composition over a substrate. The method includes providing a coating
device in flow communication with a first coating component having a first
rheological
profile and at least one other, e.g., second, coating component having a
second
rheological profile which can be the same or different than the rheological
profile of
the first coating component. The rheological profiles of the coating
components, e.g.,
two or.more coating components, can be selected such that the coating
components
-2-
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
are supplied to the apparatus and/or are mixed to provide a coating having a
desired
-ratio of the coating components, e.g., a coating having a desired amount of
one or
more materials from the first coating component and a desired amount of one or
more materials from the at least one other coating component. In one
embodiment,
the ratios of the coating components supplied to the coating device is
substantially
proportional to the relative viscosities of the coating components. In one
particular
embodiment, the coating components can be supplied under pressure, e.g., under
substantially the same pressure, to the coating device.
[0008] A coating system is provided for applying a multi-component coating
composition over a substrate. In one embodiment, the coating system includes
at
least one coating device having a first conduit and at least one other, e.g.,
second,
conduit. A first coating component having a first rheological profile can be
placed in
flow communication with the first conduit and one or more other (e.g., second)
coating components having the same or different rheological profile as the
first
coating component can be placed in flow corrimunication with the at least one
other
conduit. The coating system can include means for directing the coating
corriponents
into the coating device such that the amount of the coating components in
a'resultant
coating composition is substantially proportional to the rheological profiles
of the
coating components. The first coating component can include one or more
mater.ials,
e.g., polymeric materials, having reactive groups capable of reacting with the
functional groups of one or more materials, e.g., crosslinking materials, in
the at least
one other coating component.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Fig. 1 is a schematic, side view (not to scale) of a coating system
incorporating features of the invention;
[00010] Fig. 2 is a schematic, side view (not to scale) of another coating
system incorporating features of the invention; and
[00011] Fig. 3 is a graph of absorption versus wavelength for solutions A-D of
Example 1.
DESCRIPTION OF THE INVENTION .
[00012] As used herein, spatial or directional terms,.such as "Ieft", "right",
-
"inner", "outer", "above", "below", "top", "bottom", and the like, relate'to
the invention
as it is shown in the drawing figures. However, it is to be understood that
the
-3-
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
invention may assume various alternative orientations and, accordingly, such
terms
are not to be considered.as limiting. Further, as used herein, all numbers
expressing
dimensions, physical characteristics, processing parameters, quantities of
ingredients, reaction conditions, and the like, used in the specification and
claims are
to be.understood as being modified in all instances by the term "about".
Accordingly,
unless indicated to the contrary, the numerical values set forth in the
following
specification and claims are approximations that may vary depending upon the
desired properties sought to be obtained by the.present invention. At the very
least,
and not as an attempt to'limit the application of the doctrine of equivalents
to the
scope of the claims, each numerical value should at least be construed in
light of the
number of reported significant digits and by applying ordinary rounding
techniques.
Moreover, all ranges disclosed herein are to be understood to include the-
beginning
and ending range values and to encompass any and all subranges subsumed
therein. For example, a stated range of "1 to '10" should be considered to
include any
and all subranges between (and inclusive of) the minimum value of 1 and the
maximum value of 10; that is, all subranges beginning with a minimum value of
1 or
more and ending with a maximum value of 10 or less, e.g., 5.5 to 10. Further,
as
used herein, terms such as "deposited over", "applied over", or "provided
over" mean
deposited or provided on but not necessarily in contact with the surface. For
example, a coating composition "deposited over" a substrate does not preclude
the
presence of one or more other coating films of the same or different
composition
located between the deposited coating and the substrate. Molecular weight
quantities used herein, whether Mn or Mw, are those determinable from gel
permeation chromatography using polystyrene as a standard. Also, as used
herein,
the term "polymer" includes oligomers, homopolymers, and copolymers.
[00013] Exemplary apparatus and methods for applying a multi-component
coating onto a substrate in accordance with the present invention will now be
described with particuiar.reference to the application of a multi-component,
e.g., two
component, refinish coating onto an automotive substrate using a pneumatic
spray
device. However, it is to be understood that the invention is not limited to
use with '
refinish coatings or automotive substrates but can be practiced with any multi-
component coating type on any desired substrate. Additionally, the invention
is not
limited to use with pneumatic spray devices. Moreover, the invention is not
limited to
two component systems but can be practiced with any number of components,
e.g.,
two or more components.
-4-
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
[00014] A first exemplary coating system 10 incorporating features of the
invention is schematically shown in Fig. 1. The system 10 includes a coating
device
12. The coating device 12 can be of any conventional type, such as pneumatic,
electrostatic, gravity fed, pressure fed, etc. In the exemplary embodiment
shown in
Fig. 1, the coating device 12 is a pneumatic, siphon-feed coating gun having a
handle 14, a body 16, a nozzle 18, and a siphon tube 20. The exemplary coating
device 12 also includes a. carrier fluid conduit 22 in flow communication with
a source
24 of carrier fluid, such as a liquid or gaseous carrier fluid. in one
embodiment, the
carrier fluid is compressed air supplied at a pressure of about 10 pounds per
square
inch-gauge (psig) to 100 psig (0.7 kg/sq. cm to 7 kg/sq. cm), such as 20 psig
to 80
psig (1.4 kg/sq. cm to 5.6 kg/sq. cm), e.g., 40 psig to 60 psig (2.8 kg/sq. cm
to 4.2
kg/sq. cm). As will be appreciated by one skilled in the art, the carrier
fluid conduit 22
directs carrier fluid through apassage in the device 12 to the nozzle 18. The
inner
end of the siphon tube 20 is in flow communication with the carrier fluid
passage in
the device 12 in conventional manner. The structure and operation of a
conventional
pneumatic, siphon-feed spray gun will be well understood by one of ordinary
'skill in
the automotive refinish.art and, hence, will not be discussed in detail. One
suitable
pneumatic; siphon-feed coating'device that can be used in the practice of the
invention is a Binks Model 62 spray gun manufactured by ITW Incorporated.
[00015] In previous practice, the siphon tube 20 would be connected to.a
single container containing a mixed coating composition as described above.
However, in the practice of the invention, the siphon tube 20 =is connected
to, or,
forms,.a multi-inlefi connector 30.' In the exemplary embodiment shown in Fig.
1, the
connector 30 is depicted as a hollow, "Y-shaped" connector having a base 32, a
first
inlet or conduit 34 and a second inlet or conduit 36. The base 32 is connected
to the.
siphon tube 20, e.g., by a friction fit or by any conventional attachment
devices. The
first conduit 34 is connected to a first conduit or collection tube 40 in
flow,
, communication with a source 42 of a first coating component; e.g., one
component of
a multi-component refinish coating, and the second conduit 36 is connected to
a
second conduit or collection tube 45 in flow communication with a source 44 of
a
second coating component, e.g., another component, of the multi-component
refinish
coating. While in this exemplary embodiment only two conduits 34, 36 are
present
on the connector 30, it will be appreciated by one of ordinary skill in the
art that the.
invention is not limited to use with two-component systems. For examplejor
three-
component systems, the connector 30 could have three inlets (conduits), each
in flow
-5-
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
communication with one of the coating components. Additionally, the collection
tubes 40, 45 do not have to be separate pieces but could simply be extensions
of the
first and second conduits 34, 36.
[00016] For purposes of explanation with respect to a two-component system,
the first component can be a liquid, e.g., a solution, and can include one or
more
materiais having at least two reactive groups capable of reacting with the
functional
groups of the second component. For example, the first component can include
one
or more materials having reactive groups, such as hydroxyl, epoxy, acid,
amine,
aziridine, or acetoacetate groups, just to name a few. In one embodiment, the
first
compone,nt can include any conventional resinous or polymeric coating material
having two or more reactive groups. For example, the first component can
include
polyol, polyester, polyurethane, polysiloxane, or polyacrylate-containing
materials,
just to name a few. In one embodiment, the first component can include a
medium
molecular weight polymeric polyol, e.g., a polymeric polyol having an Mn in
the range
of 200 to 100,000, such as 1,000 to 75,000, such as 3,000 to 50,000, such as
5,000
to 20,000.
'[00017] The second component can be a liquid, e.g., a solution, and,can
include one or more materiats having functional groups configured to react
with the
reactive groups of the one or more materials in the first component to set or
cure
(e.g., crosslink with) the materials in the first component to form the
resultant coating.
For example, but not to be considered as limiting, the second component can
include
a polyisocyanate curing agent, aminoplast resins, or phenoplast resins, just
to name
a few. Examples of suitable coating components and curing agents for the
practice
of the invention are disclosed in, but are not limited to, U.S. Patent Nos.
6,297,311;
6,136,928; 5,869,566; 6,054,535; 6,228,971; 6,130,286; 6,169,150; and
6,005,045,
each of which is herein incorporated by reference in -its entirety.
[00018] Unlike previous refinish coating systems, the system 10 of the present
invention does not require the presence of supply pumps or metering pumps
between the coating component sources 42 and 44 and the coating device 12 to
meter selected amounts of the two components to the coating device 12. Rather,
in
the practice of the invention and as described below, the composition of the
resultant
coating composition applied onto a substrate 50 from the coating device 12.can
be
selected, changed, or adjusted by selecting, changing, or adjusting the
rheological
profiles of the coating components, e.g.; first and/or second coating
components. As
-6-
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
used herein, the term "rheological profile" refers to the viscosity of a
material as
measured under different sheer rates and temperature ranges.
[00019] In the practice of the invention, the rheological profiles of the
coating
components for the system shown in Fig. I can be selected or adjusted such
that
under a particular set of application conditions, e.g., temperature, carrier
fluid
pressure and/or flow rate, or shear rate, the coating components are pulled
into the
coating device 12 due to the flow of the carrier fluid through the device and
the
components are combined at a desired ratio, e.g., volume ratio, that is
substantially
proportional to the rheological profiles, e.g., viscosities, of the components
to form a
coating material of a desired. composition. As will be appreciated by one of
ordinary
skill in the art, the rheological profile of a material can be adjusted in any
conventional manner, such as by changing the molecular weight of the resinous
or
polymeric material per unit volume, the type of solvent used, the total amount
of
solids present in the composition, the addition or removal of pigmentation,
and other
ways common in the coating art. Alternatively, or in addition thereto, the
relative
amounts of the coating components drawn into the device 12 can be adjusted by
varying the diameters of the collection tubes 40 and 45.
[00020] With reference to the two-component.system described above and
shown in Fig. 1, to apply a coating composition having two parts (e.g., two
parts by
volume) of the first coating component and one part (e.g., one part by volume)
of the
second coating component, the rheological profiles of the two coating
components
can be adjusted 'such that under the selected coating conditions (e.g., .the
applied
sheer rate and temperature of the two coating components); the second coating
component has a viscosity two times (or about two times) the viscosity of the
first
coating component. As the carrierfluid (e.g., compressed air) moves through
the
coating device 12, the suction created by the air flow sucks the first and
second
coating components through the collection tubes 40, 45, the connector 30, and
into
the coating device 12 where the two components can be mixed in conventional
manner, such as by flow through a mechanical mixing device or into a mixing
chamber, before being discharged through the nozzle 18.
[00021] As will be appreciated by those skilled in the art, the rheological
profiles, e.g., viscosities, of the coating components needed to achieve a
desired
coating composition can be determined by connecting the coating components to
the
device 12 and measuring the amounts of the coating components in the resultant
composition discharged from the nozzle 18. If the amount of one or more
-7-
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
components in the resultant coating needs adjustment, the rheological profile
of such
components can be adjusted to achieve the desired coating composition. Thus,
to
achieve a 2:1 ratio, e.g., volume ratio, of the first and second coating
components in
the coating composition, the ratio of the viscosities of the first, and second
coating
components may not necessarily be exactly 1:2. As will be appreciated by one
skilled in the art, the amount of the one or more materials, e.g., polymeric
materials,
per unit volume in the first coating component and the amount of the one or
more
materials, e.g:, crosslinking materials, per unit volume in the second coating
component can be selected or adjusted such that at selected viscosities of the
first
and second coating components a selected amount of the polymeric materials and
a
selected amount of the crosslinking materials are delivered to the coating
device 12.
For example, the amounts of the materials in the coating components can be
.selected such that a 1:1 volume mix ratio of the first and second coating
components
(e.g., a 1:1 viscosity ratio) provides a 1.1:1 (or greater) equivalent ratio
of the
functional groups (e.g., NCO) of the second component to the reactive groups
(e.g.,
OH)-of the first component. In one example, the amount of the reactive groups.
and/or functional groups per unit volume of the first and/or second coating
components can be adjusted, for example, by mixing or preparing the first
and/or
second coating components with similar solvents but containing non-reactive
resins
or materials to adjust (e.g., decrease) the number of reactive or,functional
groups per
unit volume without significantly,changing the rheological profiles, e.g;,
viscosities, of
the coating components.
[00022] As mentioned earlier,, the first component and the second component
may comprise one or more materials having functional groups. In certain
embodiments of the present invention, the rheological profile of at least one
of the
first coating component and the at least one other coating component, i.e,,
the
second coating component, is selected by including in such components two or
more
materials comprising different functional groups: In such embodiments, at
least one
of the first coating component and the at least one other coating component
comprises a first material comprising functional groups of a first chemical
species
and a second material comprising functional groups of a second chemical
species,
wherein the first and second chemical species are (i) different one from the
.other and
(ii) compatible with each other. As used herein, the term "compatible with
each
other" means that the chemical species are storage-stable when combined each
8
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
other, such that the species do not react so that they component becomes too
viscous to be applied.
[00023] For example; as mentioned earlier, in certain embodiments the first
component can include one or more materials having functional groups selected
from
the hydroxyl, epoxy, amine, or aziridine chemical species. In such cases where
the
first component comprises a first material comprising hydroxyl functional
groups, the
rheological profile of the first component can be selected by including in
that
component at least one other material having functional groups of the epoxy,
amine,
acetoacetate, cabodiimide, aziridine, acrylate, or ketimine, aldimine or
aspartic ester
chemical species, including mixtures thereof. In cases where the first
component
comprises a first material comprising epoxy functional groups, the rheological
profile
of the first component can be selected by including in that component at least
one
other material having functional groups of the acetoacetate or alkoxysilane
chemical
species, including mixtures thereof. In cases where the first component
comprises a
first material comprising amine functional groups, the rheological profile of
the first
component can be selected'by including in that component at least one other
material having functional groups of the silane chemical species. In cases
where the
first camponent comprises a first material comprising aziridine functional
groups, the
rheological 'profile of the first component can be selected by including in
that
component at least one material comprising functional groups of.the
alkoxysilane
chemical species.
[00024] Moreover, as mentioned earlier, in certain embodiments the second
component can include one or more materials having functionai groups
configured to
react with the reactive groups of the one or more materials in the first
coniponent to
set or cure the materials in the first comporent. In such embodiments, the
rheological profile of the second coating component can be selected by
including in
such a component two or more materials comprising different functional groups,
as
indicated above. .
[00025] For example, in such cases where the second component comprises
a first material comprising isocyanate functional groups, the rheological
profile of the
second component can be selected by including in that component at least one
other
material: having functional groups of the epoxy, alkoxy silane, or
polyanhydride
chemical species, including mixtures thereof. In such cases where the second
component comprises a first rriaterial comprising acrylate functional groups,
the
rheological profile of the second component can be selected by including in
that
-9-
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
component at least one other material having functional groups of the alkoxy
silane
chemical species. In such cases where the second component comprises a first =
material comprising acetoacetate functional groups, the rheological profile of
the,
second component can be selected by including in that component at least one
other
material having functional groups of the acrylate chemical species. In such
cases
where the second component comprises a first material comprising anhydride
functional groups, the rheological profile of the second component can be
selected
by including in that component at least one other material having functional
groups of
the epoxy or alkoxy silane chemical species, including mixtures thereof.
[00026] In certain embodiments of the present invention, the rheological
profile
of at least one of the first coating component and the at least one other
coating
component is selected by including in such components three materials
comprising
different functional groups. In such embodiments, at least one of the first
coating
component and the at least one 'other coating component comprises a first
material
comprising functional groups of a first chemical species, a second material,
comprising functional groups of a second chemical species, and a third
material
comprising functional groups of a third chemical species, wherein the first,
second
and third chemical species are (i) different one from the other and (ii)
compatible with
each other..
[00027] For example, in certain embodiments, the first component may
comprise materials comprising hydroxyl functional groups, materials comprising
amine functional groups and materials comprising aspartic ester functional
groups.
In other embodiments, the first component may comprise materials comprising
hydroxyl functional groups, materials comprising amine functional groups and
materials comprising alkoxy silane functional groups. Moreover, in certain
embodiments; the second. component may comprise materials comprising
isocyanate
functional groups, materials comprising epoxy functional groups, and materials
comprising silane functional groups. In other embodiments, the second
component
may comprise materials comprising isocyanate functional groups, materials
comprising anhydride functional groups, and materials comprising acrylate
functional
groups.
[00028] Another coating system 60 of the invention is shown in Fig. 2. The
coating system 60 is a pressurized coating system rather than a.siphon coating
system as shown in Fig. 1. In this embodiment, the coating device 12 is in
flow
communication with a source of atomizing air 61 via an atomizing air conduit
63. The
-10-
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
first and second coating components 42, 44 can be contained within one or more
pressure vessels 62. For example, the coating components can both be present
in
the same pressure vessel 62 (as shown in Fig. 2) or can be located in separate
pressure vessels 62, each under the same or substantially the same pressure.
In the
illustrated embodiment, the pressure vessel 62 is in flow communication with a
source 64 of pressurized fluid, such as pressurized air, via a conduit 66. The
first
and second collection tubes 40, 45 can be connected to the.coating device 12
in any
conventional manner. The coating device 12 can include any conventional valve
assembly or control valve configuration, such as but not limited to needle
valves, ball
valves, and the like, to permit the coating components to be introduced into
and/or.
discharged from the coating device 12. The coating device 12 can also include
any
conventional type of mixer, such as a static mixer or in-line mixer, to mix
the two or
more coating components before they are discharged from the coating device 12.
[00029] Operation of the coating system 60 will now be described with
particular reference to applying a two-component system. Atomizing air from
the
atomizing air source 61 can be directed through the body 16 of the coating
device 12
to atomize the coating composition discharged from the nozzle 18. Such an
atomization system will be well understood by one of ordinary skill in the art
and will
not be discussed in detail herein. Essentially, the atomization air atomizes
the
coating composition discharged from the nozzle 18 to help provide a uniform
coating
mixture onto the substrate 50. In this embodiment, the first and second
coating
components 42, 44 can be placed inside the pressure vessel 62 and then the
vessel
62 closed: Pressurized fluid from the fluid soUrce 64 can then be directed
into the
pressure vessel 62 to pressurize the interior of the vessel 62. In one
embodiment,
the interior of the vessel 62 can be raised to a pressure between about 2-20
psig
(0.14 to 1.4 kg/sq. cm), such as 3-15 -psig (0.21 to 1 kg/sq, cm), such as 4-
.10 psig
(0.3 to 0.7 kg/sq. cm), such as 6-8 psig (0.4 to 0.6 kg/sq. cm). Since the
interior of
the vessel 62 is under pressure, this pressure forces the first and second
coating
components 42, 44 to. flow through the respective collection tubes 40, 45 and
into the
coating device 12 where the components can be mixed and then discharged. The
flow of the coating components into the coating device (and, hence, the
composition
of the resultant coating) is proportional, or substantialiy proportional, to
the
rheological profiles of the coating components.
-11-
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
[00030] These exemplary coating systems 10 and 60 of the invention provide
easy-to-use, low-cost methods and devices for applying a multi-component
coating
composition, such as a multi-component refinish coating, onto a substrate.
Since no
complex pumps or metering devices are required, the initial cost of the device
is
lowered and the maintenance requirements are lower than that for systems
having
such pumps and metering devices. Additionally, since the two components are
not
mixed prior to application, the curing agent can be configured to cure the
polymeric
material in a faster time.
[00031] In another aspect of the invention, for coating system 10, the
connector and associated collection tubes can be provided as a kit to modify
an
existing coating device to allow practice of the invention. Moreover, for any
coating
system (e.g., 10 or 60) of the invention, a plurality of coating components of
the same
or different rheological profiles can be provided along with information
(e.g., charts,
tables, formulas, etc.) on their rheological profiles to allow a purchaser to
select
coating components of predetermined rheological profiles to achieve a desired
final
coating composition:
[00032] The following Examples are presented to demonstrate the generaf :
principles of the invention. However, the invention should not be considered
as
limited to the specific Examples presented.
Example 1
[00033] A Binks Model 62 siphon-feed spray gun (manufactured by ITW
Incorporated) was modified by attaching a piece of Tygon tube 2 inches (5 cm)
long
having an inner diameter of 3/8 inch (0.95 cm) to the spray gun siphon tube. A
plastic Y'connector 2 inches (5 cm) long and having an inner diameter of 1/4
inch
(0.6 cm) was connected to the other end of the Tygon tube. A piece of Tygon
tube
having a length of 3 inches (7.6 cm) and an inner diameter of 3/8 inch (0.95
cm) was
attached to each branch of the Y connector to provide two collection tubes
extending
from the connector.
[00034] Cold rolled steel panels having an electrodeposited ED5000 primer
coating (the primer coated steel panels being commercially available from ACT
Laboratories Inc., of Hillsdale, MI, under the commercial designation
APR39375)
were lightly sanded by hand with 400 grit sandpaper. A urethane sealer (K36
urethane sealer commercially available from PPG Industries Inc. of Pittsburgh,
PA)
-12-
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
was applied in accordance with the manufacturer's instructions and allowed to
cure
overnight at ambient temperature. An acrylic basecoat (D9700 Global Basecoat
commercially available from PPG Industries Inc.) was spray applied to the
sealed
panels in accordance with the manufacturer's instructions and allowed to dry
at
ambient conditions for 30 minutes. The basecoated panels were then topcoated
with
clearcoats in the following manner.
[00035] Three aqueous solutions were prepared. The first (Solution A) was
distilled water. The second (Solution B) was an aqueous mixture (solution) of
distilled water and red food coloring (commercially available from McCormick
and
Co., Hunt Valley, Maryland). The third solution (Solution C) was a 1:1 mixture
by
weight of Solution A and Solution B. Separate containers holding quantities of
Solution A and Solution B were connected to the separate collection tubes and
compressed air at a pressure of 45 pounds per"square inch (3 kg/sq. cm) was
introduced through the carrier fluid conduit. As the compressed air flowed
through
the device, the Solutions.A and B were drawn up the respective collection
tubes,
through the Y connector, and into the spray device where they were mixed and
ejected through the nozzle. This mixed composition (Solution D) was collected
in a
2,000 ml beaker for analysis.
[00036] The absorbance of each solution in the range of 400 nm to 700 nm
was measured using a Perkin Elmer UV/vis spectrophotometer.Solution A, which
contained only water, had an absorbance at 523 nm equal to 0.007019: Solution
B,
which contained water and food coloring, had an absorbance ofØ77327 at 523
nm.
Solution C, which contained a 1:1 mixture of Solution A and Solution B, had an
absorbance of 0.445109 at 523 nm. Solution D, which was produced by spraying
Solution A and Solution B through the device in Fig. 1, had an absorbance of
0.435009.at 523 nm. It can, therefore, be deduced that the concentration of
food
coloring in Solution D is 97.73% of the concentration of food coloring in
Solution C
based upon the respective absorbance data. Therefore, the mix ratio of
Solutions A
and B through the gun was very nearly 1:1. Table 1 below lists the component
compositions of Solutions A-D based upon the above procedure in units of
weight
percent based on the total weight of the particular solution.
-13-
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
Table 1
Solution A Solution B Solution C Solution D
Water 100 99.9875 99.99375 99.99375
Red Food 0 0.0125 0.00625 0.00625
Coloring
[00037] A graph of absorption versus wavelength for Solutions A-D is shown in
Fig. 3. Comparing Solution C to Solution D, the invention was successful in
drawing
and mixing substantially equal portions of the pure water and dyed water
through the
spray gun as evidenced by the respective absorption curves in Fig. 3.
Example 2
[00038] A commercially available two-component automotive refinish clearcoat
(designated DC1100/DC1275 and commercially available from PPG Industries,
Inc.,
of Pittsburgh, Pennsylvania) was utilized to illustrate the ability of the
invention to mix
the two components of a commercially available coating formulation and to
apply the
mixed components as a homogeneous coating.
[00039] The DC1100 component was reduced to a viscosity of 12.5
centipoises as determined by a Brookfield LBT viscometer (No. 2 spindle, 60
rpm) by
the addition of a solvent blend (DT885 commercially available from PPG
Industries,
Inc.) and was designated Solution E. The second component of the formulation '
(DC1275) was reduced to a viscosity of 12.5 centipoises by the addition of
DT885
and designated Solution F. These individual components (Solution E and
Solution F,
respectively) were then connected to the spray device as described above and
spray
applied onto clear glass substrates. A control coating (Solution G) was pre-
mixed,
diluted, andsprayed applied onto clear glass substrates by conventional spray
equipment. The compositions of Solutions E-G are listed in Table 2 below in
units of
milliliters. Dry film thickness for the two films was measured to be 1.1. mils
for both
clearcoats as determined by a Fischerscope MMS film thickness-gauge available
from Fischer Corp.
-14-
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
Table 2
Component Solution E Solution F Solution G
DC1100 100 0 100
DC1275 0 100 100
DT885 100 100 200
Total 200 200 400
[00040] The physical properties of the two cured films (i.e., the coating
applied
by mixing Solutions E and F in accordance with the practice of the invention
as
described above and the coating applied in conventional manner from Solution
G)
were then tested for gioss, hardness, humidity resistance, and adhesion. The
results
are shown in Table 3 below.
-Table 3
Mixing Hardness Humidity Resistance
Method Gloss (secs.) Adhesion
Premixed 88 42 75 100%
(Solution G)
Mixed during 88 40 76 100%
a lication
[00041] The gloss was determined using a BYK-Gardner micro-tri gloss meter
set for measurement at a 20 angle, in accordance with the manufacturer's
instructions. The values listed in Table 3 represent the average.gloss
value.for a
minimum of three gloss measurements on.each coated substrate exaniined.
Hardness was determined using a commercially available Konig pendulum hardness
tester and placing the test panel on a table of the stand, lowering the
fulcrum onto the
test panel and then deflecting the pendulum to 6 . Hardness was recorded as
the
time in seconds that the pendulum continued to swing 30 from the center after
it had "
been released. Humidity resistance was determined by exposing the coated glass
coupons to 95% to 100% relative humidity in a 40 C (100 F) chamber for a
period of
days and then measuring the gloss using a BYK-Gardner micro-tri gloss meter
(20 angle). Adhesion was determined by scribing a pattern of 100, two-
millimeter
wide squares into the panels using a Super Cutter Guide (commercially
available
-15-
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
from Taiyu Kizai Company LTD.). Scotch brand #898 was applied over the scribed
area and the tape pulled off within 90 seconds of application. The scribed
area was
then inspected for the percent of coating remaining and the result recorded as
the
percentage adhesion of the coating, e.g., no failure is equivalent to 100
percent
adhesion. The results of the above tests (gloss, hardness, humidity
resistance, and
adhesion) indicate that the physical properties and performance of the tested
coatings are substantially the same whether applied through conventional means
or
through the coating system of theinvention.
Example 3
[00042] This example illustrates the operation of a coating system as shown in
Fig. 2 of the drawings. In this example, all viscosity measurements were
determined
using a Brookfield LVT cone and plate viscometer at a shear rate of 24
seconds'.
[00043] The following two components were utilized in this example:
Component 1: was a blend of polyols in an organic solvent
(containing methylethylketone, naptha, toluene, and acetate). Component 1 had
a
resin solids percentage of 66.80 wt.% based on the total weight of the
solution.
Component 2: was an isocyanate material. dissolved in-an organic
solvent similar to that used above in Component 1.
[00044] The two components were placed in separate containers and both
containers were placed within the same pressure vessel to maintain a constant
pressure for both components. The pressure in the pressure vessel.was
maintained
at 8 psig (0.6 kg/sq: cm) using compressed air. Rather than =being connected
to the
coating device 12, thefirst and second collection tubes 40, 45 were directed
to two
separate graduated cylinders. The flow of the first and second coating
components
due to the pressure inside the pressure vessel was maintained for a period of
60"
seconds, after which the volume of each component was. measured.
[00045] This procedure was repeated a number of times. using the same
Component 1 but varying the percent resin solids and, hence, the viscosity of
the
second coating component. These higher viscosity second components are
identified as Components 3 through 5 in Table 4 below.
-16-
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
Table 4
Test Components Viscosity Weight Volume Viscosity Volume
No. Centi oise Solids mi Difference Ratio
Component 1 49.2 cps 66.80% 142
1 0 cps 1.0:1.0
Component 2 49.2 c s 59.50% 142
Component 1 49.2 cps 66.80% 142'
2 5 cps 1.2:1.0
Com onent 3 54.2 c s 61.50% 118
Com onent 1 49.2 cps 66.80% 142
3 20 cps 1.4:1.0
Component 4 69.2 cps 63.50% 101.4
Component 1 49.2 cps 66.80% 142
4 30 cps 1.6:1.0
Component 5 79.2 cps 65.50% 88.8
[00046] As can.be seen from Table 4, the difference in viscosity of the two
components results in a difference in the flow rate through the collection
tubes and a
corresponding difference in the volume ratio of the two components delivered.
This
example illustrates that the volume of each component is dependent upon the
viscosity of the individual components under constant and equal pressure. In
this
way,.the mix ratio of a multi-component coating formulation.can be controlled
by
selecting or adjusting the various coating components to provide a mixed
coating of a
desired composition.
[00047] It will be readily appreciated by those skilled in the art that
modifications may be made to the invention without departing from the concepts
disclosed in the foregoing description. Accordingly, the particular
embodiments
described in detail herein are illustrative only and are not limiting to the
scope of the
invention, which is to be given the full breadth of the appended claims and
any and
all equivalents thereof.
Example 4
[00048] The following example illustrates that the rheological profile of at
least
one of the first coating component and the at least one other coating
component can
be selected by including in such components two or more materials comprising
different functional groups. Table 5 below lists the compositions of a two
component
coating system. Each of the listed materials was combined and blended to form
the
.coating component.
-17-
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
Table 5
Material Wei ht (grams) Solids (grams)
Com onent 1
Methyl Isobut I Ketone 34.30 --
Pent I Propionate 52.03 --
Meth I Isoamyl Ketone 55.38 --
UV Absorber 4.34 4.34
UV Absorbe 3.83 3.83
Silicone Additive 1.62 0.81
Dibutyl Tin Dilaurate 2.86 2.86
Pro o lated TMP 23.18 23.18
Acrylic Pol ol 101.46 57.33
Acrylic Pol ol 108.79 69.63
Component 2
Methyl Isobut I Ketone 26.62 --
Pent I Propionate 40.38 --
Meth I Isoam I Ketone 42.97 --
Silicone Additive 1.63 0.82
lsocyanate Oli omer 57.88 57.88
Isocyanate Oli omer 164.40 115.08
Acr
lic Silane Resin 0:83 39.38
Tetraethyl Ortho Formate 1.97 --
Chisorb 328 available from Chitec Chemical Co.
2 Sanol LS-292 available from Sankyo Co.
3 Byk 300 available from Byk Chemie.
4 Polyol TS, propoxylated trimethylol propane, available from Perstorp Inc.
A copolymer of isostearic acid, hydroxypropyl acrylate, methyl methacrylate,
styrene, and glycidal methacrylate (22.4%/23.3%/10.7%/32.4%/11.2% by weight)
at
58.8% solids in xylene.
6 A copolymer of acrylic acid, Cardura E monomer, butyl methacrylate, and
hydroxypropyl methacrylate (5.0%120.5%/25.1 %/18.1 %/29:8% by weight) at 64%
solids in xylene.
' DesN 3600, hexamethylene diisocyanate trimer, available from Bayer Corp.
8 DesN 4470, trimer of isophorone diisocyanate, available from Bayer Corp.
9 A copolymer of styrene, methacryloxy propyl trimethyoxy silane, methyl
methacrylate, butyl methacrylate, and lauryl methacrylate
(25.7%/10.0%/26.2%/18.8%/19:3% by weight) at 55.65% solids in xylene.
Test Substrate
[00049] The test substrate was an ACT cold roll steel panels (4" x 12")
supplied by ACT Laboratories, Inc. which was efectrocoated with a cationic
electrodepositable primer commercially available from PPG Industries, Inc. as
ED-
6060. Component 1 had a viscosity of 22.3 centipoises as determined by a
Brookfield LBT viscometer (No. 2 spindle, 60 rpm). Component 2 had a viscosity
of
21.8 centipoises. These components were connected to the spray device as
described above and spray applied onto the substrate. The coating was cured
for 10
-18-
CA 02571059 2006-12-14
WO 2006/009744 PCT/US2005/021159
minutes at 140 F. Dry film thickness was measured to be 2.05 mils as
determined by
a Fischerscope MMS film thickness gauge available from Fischer Corp.
[00050] The physical properties of the cured film was then tested. The results
are shown in Table 6 below.
Table 6
Gloss Hardness DOI Adhesion
88 89 80 100%
The gloss, hardness and adhesion were determined as described above for
Example
2. Distinctness of image ("DOI") of the panel was determined using a Dorigon
II DOI
Meter, which is commercially available from Hunter Lab, where a higher value
indicates better coating appearance on the test panel.
-19-
